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Tue, 6 Nov 2018 16:41:24 +0100 Subject: Re: [alsa-devel] [PATCH] ASoC: core: Invoke pcm_new() for all DAI-link To: Rohit Kumar , Takashi Iwai , CC: , , , , , , , , References: <1541075929-29323-1-git-send-email-rohitkr@codeaurora.org> <48c78f67-8178-2d07-e35d-2e4eca51ccbc@codeaurora.org> <791d4587-4db3-3ffa-331a-f79d0993ca8c@st.com> <3616f01f-6a00-6eb1-0bdd-f161b7ce15e6@codeaurora.org> From: Arnaud Pouliquen Openpgp: preference=signencrypt Autocrypt: addr=arnaud.pouliquen@st.com; prefer-encrypt=mutual; keydata= xsFNBFZu+HIBEAC/bt4pnj18oKkUw40q1IXSPeDFOuuznWgFbjFS6Mrb8axwtnxeYicv0WAL rWhlhQ6W2TfKDJtkDygkfaZw7Nlsj57zXrzjVXuy4Vkezxtg7kvSLYItQAE8YFSOrBTL58Yd d5cAFz/9WbWGRf0o9MxFavvGQ9zkfHVd+Ytw6dJNP4DUys9260BoxKZZMaevxobh5Hnram6M gVBYGMuJf5tmkXD/FhxjWEZ5q8pCfqZTlN9IZn7S8d0tyFL7+nkeYldA2DdVplfXXieEEURQ aBjcZ7ZTrzu1X/1RrH1tIQE7dclxk5pr2xY8osNePmxSoi+4DJzpZeQ32U4wAyZ8Hs0i50rS VxZuT2xW7tlNcw147w+kR9+xugXrECo0v1uX7/ysgFnZ/YasN8E+osM2sfa7OYUloVX5KeUK yT58KAVkjUfo0OdtSmGkEkILWQLACFEFVJPz7/I8PisoqzLS4Jb8aXbrwgIg7d4NDgW2FddV X9jd1odJK5N68SZqRF+I8ndttRGK0o7NZHH4hxJg9jvyEELdgQAmjR9Vf0eZGNfowLCnVcLq s+8q3nQ1RrW5cRBgB8YT2kC8wwY5as8fhfp4846pe2b8Akh0+Vba5pXaTvtmdOMRrcS7CtF6 Ogf9zKAxPZxTp0qGUOLE3PmSc3P3FQBLYa6Y+uS2v2iZTXljqQARAQABzSpBcm5hdWQgUG91 bGlxdWVuIDxhcm5hdWQucG91bGlxdWVuQHN0LmNvbT7CwX4EEwECACgFAlZu+HICGyMFCQlm AYAGCwkIBwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEP0ZQ+DAfqbfdXgP/RN0bU0gq3Pm1uAO 4LejmGbYeTi5OSKh7niuFthrlgUvzR4UxMbUBk30utQAd/FwYPHR81mE9N4PYEWKWMW0T3u0 5ASOBLpQeWj+edSE50jLggclVa4qDMl0pTfyLKOodt8USNB8aF0aDg5ITkt0euaGFaPn2kOZ QWVN+9a5O2MzNR3Sm61ojM2WPuB1HobbrCFzCT+VQDy4FLU0rsTjTanf6zpZdOeabt0LfWxF M69io06vzNSHYH91RJVl9mkIz7bYEZTBQR23KjLCsRXWfZ+54x6d6ITYZ2hp965PWuAhwWQr DdTJ3gPxmXJ7xK9+O15+DdUAbxF9FJXvvt9U5pTk3taTM3FIp/qaw77uxI/wniYA0dnIJRX0 o51sjR6cCO6hwLciO7+Q0OCDCbtStuKCCCTZY5bF6fuEqgybDwvLGAokYIdoMagJu1DLKu4p seKgPqGZ4vouTmEp6cWMzSyRz4pf3xIJc5McsdrUTN2LtcX63E45xKaj/n0Neft/Ce7OuyLB rr0ujOrVlWsLwyzpU5w5dX7bzkEW1Hp4mv44EDxH9zRiyI5dNPpLf57I83Vs/qP4bpy7/Hm1 fqbuM0wMbOquPGFI8fcYTkghntAAXMqNE6IvETzYqsPZwT0URpOzM9mho8u5+daFWWAuUXGA qRbo7qRs8Ev5jDsKBvGhzsFNBFZu+HIBEACrw5wF7Uf1h71YD5Jk7BG+57rpvnrLGk2s+YVW zmKsZPHT68SlMOy8/3gptJWgddHaM5xRLFsERswASmnJjIdPTOkSkVizfAjrFekZUr+dDZi2 3PrISz8AQBd+uJ29jRpeqViLiV+PrtCHnAKM0pxQ1BOv8TVlkfO7tZVduLJl5mVoz1sq3/C7 hT5ZICc2REWrfS24/Gk8mmtvMybiTMyM0QLFZvWyvNCvcGUS8s2a8PIcr+Xb3R9H0hMnYc2E 7bc5/e39f8oTbKI6xLLFLa5yJEVfTiVksyCkzpJSHo2eoVdW0lOtIlcUz1ICgZ7vVJg7chmQ nPmubeBMw73EyvagdzVeLm8Y/6Zux8SRab+ZcU/ZQWNPKoW5clUvagFBQYJ6I2qEoh2PqBI4 Wx0g1ca7ZIwjsIfWS7L3e310GITBsDmIeUJqMkfIAregf8KADPs4+L71sLeOXvjmdgTsHA8P lK8kUxpbIaTrGgHoviJ1IYwOvJBWrZRhdjfXTPl+ZFrJiB2E55XXogAAF4w/XHpEQNGkAXdQ u0o6tFkJutsJoU75aHPA4q/OvRlEiU6/8LNJeqRAR7oAvTexpO70f0Jns9GHzoy8sWbnp/LD BSH5iRCwq6Q0hJiEzrVTnO3bBp0WXfgowjXqR+YR86JPrzw2zjgr1e2zCZ1gHBTOyJZiDwAR AQABwsFlBBgBAgAPBQJWbvhyAhsMBQkJZgGAAAoJEP0ZQ+DAfqbfs5AQAJKIr2+j+U3JaMs3 px9bbxcuxRLtVP5gR3FiPR0onalO0QEOLKkXb1DeJaeHHxDdJnVV7rCJX/Fz5CzkymUJ7GIO gpUGstSpJETi2sxvYvxfmTvE78D76rM5duvnGy8lob6wR2W3IqIRwmd4X0Cy1Gtgo+i2plh2 ttVOM3OoigkCPY3AGD0ts+FbTn1LBVeivaOorezSGpKXy3cTKrEY9H5PC+DRJ1j3nbodC3o6 peWAlfCXVtErSQ17QzNydFDOysL1GIVn0+XY7X4Bq+KpVmhQOloEX5/At4FlhOpsv9AQ30rZ 3F5lo6FG1EqLIvg4FnMJldDmszZRv0bR0RM9Ag71J9bgwHEn8uS2vafuL1hOazZ0eAo7Oyup 2VNRC7Inbc+irY1qXSjmq3ZrD3SSZVa+LhYfijFYuEgKjs4s+Dvk/xVL0JYWbKkpGWRz5M82 Pj7co6u8pTEReGBYSVUBHx7GF1e3L/IMZZMquggEsixD8CYMOzahCEZ7UUwD5LKxRfmBWBgK 36tfTyducLyZtGB3mbJYfWeI7aiFgYsd5ehov6OIBlOz5iOshd97+wbbmziYEp6jWMIMX+Em zqSvS5ETZydayO5JBbw7fFBd1nGVYk1WL6Ll72g+iEnqgIckMtxey1TgfT7GhPkR7hl54ZAe 8mOik8I/F6EW8XyQAA2P Message-ID: <4f22e4e5-84f0-1560-1ba7-5e77d44fd312@st.com> Date: Tue, 6 Nov 2018 16:41:23 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <3616f01f-6a00-6eb1-0bdd-f161b7ce15e6@codeaurora.org> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [10.75.127.45] X-ClientProxiedBy: SFHDAG3NODE3.st.com (10.75.127.9) To SFHDAG3NODE1.st.com (10.75.127.7) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-11-06_07:,, signatures=0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Rohit On 11/5/18 7:14 PM, Rohit Kumar wrote: > Hello Arnaud, > > > On 11/5/2018 4:43 PM, Arnaud Pouliquen wrote: >> Hello Rohit, >> >> On 11/2/18 1:06 PM, Rohit Kumar wrote: >>> On 11/2/2018 1:12 PM, Takashi Iwai wrote: >>>> On Thu, 01 Nov 2018 13:38:49 +0100, >>>> Rohit kumar wrote: >>>>> Remove no_pcm check to invoke pcm_new() for backend dai-links >>>>> too. This fixes crash in hdmi codec driver during hdmi_codec_startup() >>>>> while accessing chmap_info struct. chmap_info struct memory is >>>>> allocated in pcm_new() of hdmi codec driver which is not invoked >>>>> in case of DPCM when hdmi codec driver is part of backend dai-link. >>>>> >>>>> Below is the crash stack: >>>>> >>>>> [   61.635493] Unable to handle kernel NULL pointer dereference at >>>>> virtual address 00000018 >>>>> .. >>>>> [   61.666696]   CM = 0, WnR = 1 >>>>> [   61.669778] user pgtable: 4k pages, 39-bit VAs, pgd = >>>>> ffffffc0d6633000 >>>>> [   61.676526] [0000000000000018] *pgd=0000000153fc8003, >>>>> *pud=0000000153fc8003, *pmd=0000000000000000 >>>>> [   61.685793] Internal error: Oops: 96000046 [#1] PREEMPT SMP >>>>> [   61.722955] CPU: 7 PID: 2238 Comm: aplay Not tainted 4.14.72 #21 >>>>> .. >>>>> [   61.740269] PC is at hdmi_codec_startup+0x124/0x164 >>>>> [   61.745308] LR is at hdmi_codec_startup+0xe4/0x164 >>>>> >>>>> Signed-off-by: Rohit kumar >>>> Did you check whether all drivers have no side-effect by this change? >>>> The hdmi-codec isn't the only driver that has pcm_new ops, so we have >>>> to make sure that such a fundamental change wouldn't bring any >>>> regressions. >>>> >>> Below are the drivers calling pcm_new() other than hdmi codec driver. >>> sound/soc/meson/axg-frddr.c >>> sound/soc/meson/axg-toddr.c >>> These two drivers are frontend DAI drivers and should not be impacted >>> because of this. >>> >>> Other than this, pcm_new() is called from sound/soc/stm/stm32_sai_sub.c >>> I could not get much info about this driver. However, it is just adding >>> kcontrols in pcm_new() which uses internal private structs in >>> get()/put(). >>> Olivier Moysan can too confirm on this. >> First, i'm answering  for Olivier: no regression identified for the SAI >> driver, it is not a DPCM driver. >> >> Then i have a concern about the call of pcm_new for a no-PCM backend. >> Does it make sense? In DPCM concept, the backend is not linked to the >> PCM device... >> >> Instead, I would suggest that you add protection in HDMI_codec on >> chmap_info pointer. >> >> The drawback would be that the control is no more available...do you >> need it? > I don't need chmap_info, but ELD kcontrol is also defined in pcm_new() > which > we need. We should probably update the driver to make it compatible with > DPCM. Any suggestions? I would say force device to 0 if no_pcm (need probably to create the control in hdmi_of_xlate_dai_id instead of hdmi_codec_pcm_new). But keep in mind that solution has to work in case of multi HDMI codec instances, perhaps using prefix... Anyway, i'm not a DPCM expert so perhaps more elegant solutions exist. Regards Arnaud >> Regards >> Arnaud >> >>> Thanks, >>> Rohit >>>> thanks, >>>> >>>> Takashi > Thanks, > Rohit >